This invention relates to torque wrenches and more particularly to improvements in such devices which render them not only most simple and economical to fabricate and devoid of complexity yet endow them with features of utility equal to and beyond those of the wrenches considered as the "Cadillacs" of the prior art which are much more expensive and involved as to their construction. In this context, the embodiments of the present invention may be further characterized as being more efficient and satisfactory in use in a wider variety of applications and environments and affording an operator self insurance against excessive application of torque in their use.
A torque wrench is used in application to fastening devices in the nature of bolts, nuts, screws and the like to insure a tight application thereof while avoiding the application thereto of excessive torque, the latter being adverse to and sometimes destructive of the structural integrity of the fasteners and/or the elements which they are intended to clamp or otherwise fix in place.
Applying a uniform level or torque to each of a number of fasteners required to achieve a given assembly of parts, let alone insuring adequate and avoiding excessive application of torque to any single fastener is not always easy. This is not surprising considering the fact that the person using a hand tool such as a torque wrench must keep his mind and eyes on his work and the attitude of his tool in its application to avoid cocking of slippage and disengagement of the tool with possible damage to the work product or its parts and loss of time in the work procedure while at the same time observing read-out of the torque being applied, too little or excessive amounts of which are both unacceptable. Consider further that the user is never rigid and fixed as to his position while he works, by reason of which the problem of parallax enters into his efforts to accurately read the position of a pointer with reference to the torque scale he must observe. This problem is compounded where, as often is the case, the position and location of the user of the torque wrench relative to his work or the environment in which he is working makes it inconvenient or even impossible to readily observe a torque read-out device while he is fixing a fastener in place.
Some torque wrenches of the prior art have endeavored to avoid problems of the nature described above by ignoring the need for the convenience and savings inherent in the provision of a simply constructed and arranged torque read-out means and concentrating on providing complex and costly torque limiting and disabling means within the wrench. However, this is obviously not the best solution and does not afford the required versatility and simplicity and economy of design and use that is most desirable and made possible by the present invention.
The prior art most pertinent to the present invention, as far as those substantively involved in the preparation of this disclosure are aware, is exemplified by the attached exhibit, namely as catalogue sheet of Saint-Chi Industries Co., Ltd., which reveals a torque wrench comprising a handle having a grip at one end and a driver at the opposite end, the driver mounting an indicator rod which projects over the handle in the direction of its grip to have the projected extremity of the rod applied to a scale imprinted on a flat horizontal plate located transversely of and in connection with the handle, immediately of the grip.